<?php
/*
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the LGPL. For more information, see
 * <http://www.doctrine-project.org>.
 */

namespace Doctrine\ORM\Id;

use Serializable, Doctrine\ORM\EntityManager;

/**
 * Represents an ID generator that uses a database sequence.
 *
 * @since 2.0
 * @author Roman Borschel <roman@code-factory.org>
 */
class SequenceGenerator extends AbstractIdGenerator implements Serializable {
	private $_allocationSize;
	private $_sequenceName;
	private $_nextValue = 0;
	private $_maxValue = null;
	
	/**
	 * Initializes a new sequence generator.
	 *
	 * @param Doctrine\ORM\EntityManager $em The EntityManager to use.
	 * @param string $sequenceName The name of the sequence.
	 * @param integer $allocationSize The allocation size of the sequence.
	 */
	public function __construct($sequenceName, $allocationSize) {
		$this->_sequenceName = $sequenceName;
		$this->_allocationSize = $allocationSize;
	}
	
	/**
	 * Generates an ID for the given entity.
	 *
	 * @param object $entity
	 * @return integer|float The generated value.
	 * @override
	 */
	public function generate(EntityManager $em, $entity) {
		if( $this->_maxValue === null || $this->_nextValue == $this->_maxValue ) {
			// Allocate new values
			$conn = $em->getConnection();
			$sql = $conn->getDatabasePlatform()->getSequenceNextValSQL( $this->_sequenceName );
			$this->_nextValue = $conn->fetchColumn( $sql );
			$this->_maxValue = $this->_nextValue + $this->_allocationSize;
		}
		return $this->_nextValue++;
	}
	
	/**
	 * Gets the maximum value of the currently allocated bag of values.
	 *
	 * @return integer|float
	 */
	public function getCurrentMaxValue() {
		return $this->_maxValue;
	}
	
	/**
	 * Gets the next value that will be returned by generate().
	 *
	 * @return integer|float
	 */
	public function getNextValue() {
		return $this->_nextValue;
	}
	
	public function serialize() {
		return serialize( array( 'allocationSize' => $this->_allocationSize, 'sequenceName' => $this->_sequenceName ) );
	}
	
	public function unserialize($serialized) {
		$array = unserialize( $serialized );
		$this->_sequenceName = $array['sequenceName'];
		$this->_allocationSize = $array['allocationSize'];
	}
}
